Description of problem:
To use the new virtio capabilites available in kvm 60, special command line
paramaters need to be passed to kvm. There should be a way to specify that a
device should use virtio in the libvirt xml.
I propose adding a "model" attribute to the interface element in the XML to be
able to specify the type of NIC to emulate, e.g. 'virtio'.
For the disk virtio I propose adding an 'interface' attribute to target element
(inside the disk element). This interface could then be set to 'virtio', 'ide',
'scsi', etc..